Moscow Polytechnic University, Moscow, Russia

R. L. Shatalov, Dr. Eng., Prof., Dept. of Materials Forming and Additive Technologies, e-mail: mmomd@mail.ru
E. E. Zagoskin, Postgraduate Student, Dept. of Materials Forming and Additive Technologies, e-mail: zagoskin86@yandex.ru

Bogorodsky branch of JSC SPA Pribor, Noginsk, Russia
V. A. Medvedev, Cand. Eng., Technologist, e-mail: 10-bmt@mail.ru

The results of a study using the QForm software package and an experiment are presented, determining factors affecting the quality characteristics of vessels made of steel 50 produced on a three-roll screw mill 30–80 and a horizontal press, which are part of the rolling and pressing line of the BF JSC NPO Pribor enterprise. Modeling of the process allowed us to establish that when rolling along the length of the workpiece and a solid piercing mandrel made of 4X5MFS steel, an unevenness of temperature is formed, which is associated with heat transfer during the formation of the cavity. It is shown that the temperature unevenness along the length of the vessel is 200 °C, and the stitching mandrel is 250 °C. At the same time, the bottom part of the vessel and the toe of the mandrel are more heated to 1140 °C and 600 °C compared to the upper part of the vessel and the base of the mandrel 940 and 350 °C, respectively. A hundred-fold simulation of the firmware process allowed us to establish the influence of the heating temperature of the mandrel on its wear of about 0.64 and 2.4 mm from tangential and normal stresses of about, respectively, which does not allow for the specified geometric dimensions of semi-finished products. Modeling has established that the temperature unevenness after rolling persists after stamping and ranges from 950 to 750 °C, the temperature difference is the same 200 °C, which affects the conditions of subsequent cooling when simulating quenching in mineral oil. At the same time, an unevenness of indicators along the length of semi-finished products is formed: hardness from 460 to 740 HV and strength from 1050 to 1700 MPa. The recommendations of repeated heat treatment are given, allowing to align the mechanical properties of rolled products along the length: hardness 500 HV, tensile strength 1000 MPa. The design of a water-cooled mandrel has been developed and tested on a screw mill 30–80, the use of which makes it possible to reduce the temperature of the nose to 400 °C at the base to 150 °C, which positively affects its service life, which increases up to 2.7 times. At the same time, dimensions are formed that meet the requirements of the design documentation for the cavity of the vessel made of steel 50 presented by the BF JSC NPO Pribor. An adequate regression equation is constructed that establishes a linear dependence of the change in the diameter of the cavity on the number of vessels released.

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